The present invention relates to polymeric agents which are useful as water-absorbents, and in particular, to polymeric agents which are useful in removing water from numerous systems.
Water-swellable polymers have found various uses as absorbents for water. Examples of such polymers are disclosed in U.S. Pat. Nos. 3,926,891; 4,190,562 and 4,293,609. Unfortunately, such known water-swellable polymers are either non-ionic water-swellable polymers, or polyanionic water-swellable polymers containing anions of weak acids such as carboxylic acids. The weakly acidic groups only function in the ionic form when the pH of the system is above the pK of the acidic group. Thus, the known water-swellable polymers have not been effective in applications in which the pH is below about 4.
In view of the deficiencies of the prior art, it would be highly desirable to provide a means for effectively absorbing an aqueous medium which is acidic in nature.